Dental articulator



E. J. FRANWIC K DENTAL ARTICULATOR April. 1, 1941.

Filed Nov. 14, 1959 Patented Apr. 1, 1941 DENTAL ARTICULATOR Edmond J.Franwick, Buffalo, N. Y., assignor to Hanan Engineering Company, Inc.,Buffalo, N. Y., a corporation of New York Application November 14, 1939,Serial No. l,357

3 Claims.

My invention relates to an improvement in dental articulators which, aswill be clear to those skilled in the art, is for the purpose ofsupporting dentures or models on plates or bases for manipulation in thesame or equivalent relation to that which they are to occupy when placedin the mouth of a patient.

In the process of mounting a set of models on an articulator of thiskind, it is necessary that the lower model be mounted in what is knownas centric relation to the upper model, or in other words in suchrelationship to each other as the jaws of a human being have when bothcondyle heads rest in their rearmost positions within the sockets of thefossae without strain. Very often a lower denture is unintentionallymounted with respect to the upper denture in protruded or lateralrelation on the articulator. Such a mounting would not present the truerelationship between instrument and anatomy so essential to theconstruction of satisfactory dentures. It must be understood thatmounting records made in the mouth are made in centric relation. Whenmounting such records in the instrument, the jaw members'of theinstrument must be in centric relation. Articulators of the type inwhich this invention is embodied would permit lateral or protrudedmounting of one of the models in the articulator; but this is guardedagainst by the use of this invention.

This invention is designed for use on the type of articulator patentedby Rudolf L. I-Ianau May 8, 1928, No. 1,668,845, in which condylarelements are provided and arranged in triangular relation with respectto an incisal guide, and it is the object of this invention to overcomecertain inaccuracies in the manipulation of the articulator when,through carelessness on the part of the operator, the co-relation of theparts desired is not maintained.

Another object of my invention is to providea simple and efiicientlocking device for maintaining the upper jaw member of the articulatorin centric relation to the lower jaw member, said locking deviceco-acting with projecting parts of said upper jaw member to retaincentric relation between the two jaw members regardless of anyadjustment made to the articulator.

With these and other objects in view to appear hereinafter, thisinvention consists in the novel features of construction and in thearrangement and combination of parts to be hereinafter described andmore particularly pointed out in the subjoined claims.

In the drawing forming part of this application- Fig. 1 is a sideelevation of an articulator equipped with my invention in what I nowconsider preferred form.

Fig. 2 is a front elevation of the same.

Fig. 3 is a top plan view.

Fig. 4 is a cross section taken on line 44, Fig. 2, with the condylarhead adjusted to a position different from that shown in Fig, 2.

Fig. 5 is a vertical section taken on line 55, Fig. 3.

In the particular articulator illustrated in the drawing, the numeral 6designates the frame or support, which comprises a base 1 having threeextremities 8, 9 and Ill in triangular relation, and from two of whichrise transversely spaced uprights or posts II which may be referred toas condylar posts. In the third extremity is arranged an incisal guidedevice [2. The condylar posts are at the rear of the frame, while theincisal guide device is at the front of the frame. It will be clear,therefore, that the base, although not an exact triangle, approachestriangular formation in that it is wide at the rear end and graduallynarrowed toward the front. The base has a mounting I3 secured to itsupper face by means of a securing screw l4 passing through the base fromthe bottom and threaded into said mounting. This mounting is centered atthe intersection of a plane passing centrally between the condylar postsand a plane passing transversely between and equidistant from thecondylar posts and the incisal guide.

At the three corners of the triangular base 1, feet were provided, andat the two rear angles of said base circular depressions l6 are formed.Each of the condylar posts II has a circumferential flange I! at itslower end fitted into its cooperating depression IB and a hollowcircular condylar head l8 at its upper end. The condylar posts arerotatably adjustable within the circular depressions in the base, andfor this purpose graduation marks may be provided on the base adjacenteach of the circumferential flanges l1 and each of the flanges with anindicating mark for registration with any of the said graduation marksso as to determine the exact degree of rotation to which the condylarposts may be adjusted.

Threaded into the base 1 of the articulator and overlying thecircumferential flanges of the condylar posts are securing screws l9which serve to secure the condylar posts in any adjusted position.

Rotatably mounted in each condylar head l8 is a disk having a slot 2|extending diametrically from one point of its edge inwardly beyond theaxis of said disk, preferably in rectilinear manner. The oppositelongitudinal walls of said slot are concaved, as clearly shown in Fig.5. Each condylar head has a segmental slot 22 extending along a portionof its circular wall, preferably forwardly from the highest part of saidhead, and each disk has a screw stud 23 fastenedtherein which extendsoutwardly through the segmental slot of the head and has a clamping nut24 threaded thereon and adapted to bear against the outer surface of thehead to fasten the disk within the latter in any desired rotatively'adjusted position. It will be apparent, therefore, that since said disks20 are rotatively adjustable in the condylar heads l8 and the latter arerotatively adjustable in the base of the device, said disks areadjustable angularly as well as rotatively; the angular adjustment beingeffective by rotation. of the condylar posts and the rotative adjustmentbeing made within the condylar heads within the upper ends of saidposts.

,Arranged within the slots 2| of the rotatably adjustable disks arespherical or substantially spherical mountings or bearings 25 which areretained against lateral movement within said slots and therefore withinsaid disks, by reason of their spherical surfaces fitting the concavedlongitudinal walls of said slots. The slots 2| may be termed radialguide slots or guideways, and the spherical mountings. or bearings 25,condylar spheres or balls. Said condylar spheres or elements 25 aremovable lengthwise within said guideways and they are normallyaccurately centered by means of stops 2 6 in the form of adjustablescrews threaded intothe disks 20. This assures accurate centering of thecondylar elements with respect to the axes on which the condylar i posts[I rotate. The condylar spheres or elements 25 are free to movelengthwise in the slots or guideways 2| of the rotatively adjustabledisks 2|), but by reason of their being confined within the concavedwalls of said guideways are held against lateral movement.

21 designates the upper bracket or dentureholding member, which forconvenience may be referred to as the upper jaw member, while the base 1may be termed the lower jaw member.

This upper jaw member, in the form shown, is comparatively narrow, andat its rear end has a downwardly-directed portion 28 slightly inclinedrearwardly and provided. at its lower end withoppositelaterally-directed extensions 29 in which are secured pivot rods orshafts 30 which are reduced. in diameter along their outer portions, asat 3|, to form outwardly-facingv shoulders 32. The outer reducedportions of said rods extend through the spherical condylar elements 25and when the latter are in the position in which the dentures or modelson the upper and lower jaw members are in centric relation, the saidshoulders bear against said spherical condylar elements and saidspherical elements against the stops 26. This prevents transversemovement of at least the rear end of the upper jaw member under alladjustments of the articulator so long as the centers of said sphericalcondylar elements coincide with the axes of the disks 2% in which theyare located.

The said rods or shafts are threaded into or otherwise fastened to theopposite laterally-directed extensions 29 so that they practically forma part of the upper jaw member and serve as a pivot for the same.Secured to the under side of the upper jaw member 2! is a mounting 33 towhich the base of an upper denture or model is to be secured, saidmounting being held in position by a thumb screw 34 passed through theupper jaw member and threaded into said mounting. The upper jaw memberhas a depending portion 35 at its front end in which an incisal pin orstem 36 is adjustably fitted. The said pin or stem is held in anyadjusted position by means of a thumb screw 31 extending into saiddepending portion and bearing against said pin or stem. The lower end ofthis incisal pin or stem is tapered, as at 38, and adapted forco-.action with the-incisal guide device l2 and adjusted as clearly setout in the aforesaid Patent No. 1,668,845. The slots or guideways 2| inthe disk 20 are normally in horizontal position, and since these disksare adapted to be rotatably adjusted within the condylar heads, the saidslots or guideways may be positioned at an angle to the horizontal,either above or below the latter.

For the purpose of readily determining the exact angularity orinclination of these slots or guideways, each disk may have anindicating mark formed thereon, and the condylar head a segmental seriesof graduation marks; but since this forms no part of my invention and isfully described in the aforesaid patent, the operation and adjustment ofparts can be easily determined. The centers of the spherical condylarelements 25 may be compared with the condyle socket centers of the humanmaxillae, and when the incisal pin or stem 36 rests on the incisal guidel2 and the spherical condylar elements are against the stops 25, thedentures or models secured to the mountings l3 and 33 are held in theposition of centric relation in the articulator.

The construction described permits construction of the jaw members andmanipulation of the same to meet the requirements of the particularindividual for whom the dentures or other fittings are to be provided,all of-which is clearly set out in the aforesaid patent. Very often alower denture or model is unintentionally mounted with respect to theupper in protruded relation on the articulator, and under suchconditions the spherical condylar elements 25 are spaced somewhat fromthe stops 26. Should one of these spherical condylar elements only be intouch with its co-opcrating stop, there would be a lateral deviationfrom the centric relation of the dentures or models mour ited on the jawmembers. It will be clear that the relation from the condylar axis ofthe articulator changes with every position, and for this reason I haveprovided means, which may be termed a locking device, to lock the jawmembers in centric relation, regardless of what position the condylarposts II or the disks adjustable in the upper ends of the posts are in.With this in view I have provided lock latches 39, one for. eachcondylar head. Each latch comprises two angular arms 1w, 4| disposed atan angle to each other; the arm 40 being strai ht-lined and having itslower end pivotally secured to the disk within the co-operating condylarhead, and its other arm 4| being formed arcuate and describing an arc ofa circle having a pivot 42 as its center. The arcuate or curved arm 4|is provided with a slot 43 through which is passed a screw stud 44fastened into the disk 20 and which projects outwardly from said disk.Surrounding said screw" stud is a washer 45, and threaded onto the outerprojecting portion of said stud is a thumb nut 46 which, when tightenedagainst the washer,

will cause the latter to firmly press the locking device against theside of the disk and condylar head in any position to which said lockingdevice may be positioned. The forward edge of the straight-lined arm 46serves as a contact face for the projecting ends of the pivot rods 30,and thus, regardless of the angularity to which the condylar heads maybe positioned, the locking devices will serve to hold the sphericalcondylar elements 25 against their respective stops 26. When thearticulator is locked by these locking devices, the only movementpossible would be a rotating movement of the upper jaw member around thearticulator condylar .axis. Thus, regardless of the adjustment of thecondylar posts and consequently the angularit of the condylar heads, andalso regardless of the rotative adjustment of the disks 2!] within thecondylar heads, centric relation of the jaw members is assured.

Without the use of these locking devices it has been necessary to adjustthe condylar 'heads in parallel relation and parallel with thelongitudinal center of the articulates, and even under such conditions,through carelessness of the operator, it was possible to have one of thespherical condylar elements move away from its cooperating stop, withthe result that when mounting dentures or models on the jaw members, andparticularly the lower denture or model with respect to the upper, thelower denture or model would be off centric relation. It has also beenfound that operators inadvertently overlooked positioning co-ndylarheads against stops 2% when the last use of th articulator resulted apositioning of these heads otherwise. Therefore, the locking of thepivot rods or shafts by means of my improved locking device assures acentric relation of the jaw members and consequently of the dentures ormodels regardless of the position of the condylar posts, and condylarheads or parts adjustable therein. In order, therefore, to guard againstany mishap in the mounting of the dentures or models on the respectivejaws of the articulator, the operator first locks the condylar elements25 against the stops 26 provided in the disks 2!]. He then proceeds tosecure the dentures or models to their respective jaw members withassurance they will be fastened in centric relation, after which thelocking devices may be unlocked and moved out of the way. Theangularprovements may be applied to any universally operated artioulatorembodying the principles set out in the anticulator of said patent.

Having thus described my invention, what I claim is:

1. In a dental articulator having a horizontally pivoted jaw memberprovided with opposite project-ing pivots, and spaced-apart condylarheads rotatably adjustable on an axis at an angle to the horizontal andthrough which the pivots of said jaw member extend; a lock devicepivotally secured to each of said oondylar heads, each having astraight-lined arm extending from its pivotal point and engaging thepivots of said jaw member and an arcuate arm extending from the free endof said straight-lined arm and describing an arc of a circle having thepivot of said lock devic as its center, said arcuate am having a slotformed lengthwise therein, and means passing through said slot forlocking said arm in desired position.

-2. In a dental articulator having spaced-apart condylar heads rotatableon vertical axes and disks rotatable within said heads having guidewaysextending inwardly from their peripheries and a horizontally pivoted jawmember having its pivots extending through the guideways of said disks;locking means to maintain said jaw member in centric relationirrespective of the ro tative adjustment of said condylar heads or theadjustment of said disks within said heads comprising an angular lockarm for each of said disks, each lock arm having a straight-lined memberpivotally secured to the outer face of its (Jo-operating disk and amember extending forwardly from said straight-lined member and having anarcuate slot formed therein whose center is the pivot ofits lock arm,.and a locking element co-operating with said slot to lock said lock armin either looking or unlocking position, one edge of said straight-luredmember bearing against the pivots of said jaw member to maintain them atthe ends of their movements in one direction within said guideways andto assure centric maintenance of said jaw member.

3. In a dental articulator having a pivoted jaw member provided withopposite project-ing pivots, and spaced-apart oondylar heads rotatablyadjustable at an angle to the horizontal and having elements thereinrotatable on horizontal axis through which the pivots of said jaw memberextend and in which they are radially adjustable; a lock devicepivotally secured to each of said condylar heads co -acting with thepivot projeoting through the latter, each lock device having an arcuateslot whose center is the pivot of the lock device in which it is formedand having also clearance to enable its adjustment with respect to theoo-acting pivot of said jaw member, the clearances of said lock devicesforming stops thereon to be engaged by the pivots of said jaw members,and means on the rotatable elements within said condylar heads passingthrough said arcuate slots for fastening said lock devices in desiredpositions.

EDMOND J.

